The invention relates to a process for the treatment of water contaminated with products, in particular hydrocarbon or petroleum products such as oil and petrol, but also contaminants such as tallow, vegetable oil, and light solid plastic or other particles. Such contaminated water may include run off water from a petroleum storage, loading or transferring station, or from any other source where a contaminated water run off is anticipated, for example in carparks, chemical plants, oil refineries, machine shops, abattoirs and the like.
In known processes, contaminated water may be collected from a source area potentially containing contaminants, and stored in a receptacle. The contaminated water may then be either allowed to flow directly into open drains or sewers, or more usually be treated to remove as much of the contaminant as possible before the water stream is allowed to leave the site. Such treatment processes for cleaning water contaminated with oil or petrol generally involve pumping the contaminated water into an above ground tank or vessel, which contain a series of parallel plates or baffles which allow the oil droplets in the water mixture to rise to the surface of the vessel under the normal action of gravity settling, from where the oil is generally skimmed from the top and into a drum or other storage container for later removal from the site. The cleaner water stream is generally allowed to enter the open drains or sewers. These vessels are generally of a category called Plate Separators, or Corrugated Plate Interceptors, (CPI).
There are a number of difficulties and dangers with the Plate Separator and CPI type systems, the result of which is that the water quality produced is often not of an acceptable level to be safely or legally discharged into open drains or sewers, and may contain enough residual petroleum or other inflammable contaminant to produce a potentially explosive mixture in the presence of an ignition source, or be a pollutant to the environment.